1. Field of the Invention
The present invention relates to a contact used in a socket, and especially to a contact of a ZIF socket.
2. Description of Prior Art
As computer functions continue to expand, a Central Processing Unit (CPU) requires an increasing number of memory processing units, thus transmission paths become more compact and complex. Therefore, securely and stably connecting the chipset to a circuit board for ensuring accurate signal transmission is very important. A socket for connecting a CPU of a computer related to the present invention is disclosed in the U.S. Pat. Nos. 3,676,832; 4,498,725; and 4,988,310.
Referring to FIGS. 1A, 1B, 2A and 2B, a socket 6 for connecting a CPU (not shown) to a circuit board (not shown) with zero insertion force generally includes a dielectric base 601, a plurality of contacts 60 (only one shown) received in the dielectric base 601 and a cover 602 covering the dielectric base 601 and supporting the CPU. The cover 602 together with the CPU, is movable relative to the dielectric base 601 whereby pins (only one shown) 7 of the CPU electrically connect with the contacts 60 of the socket 6.
The contacts 60 of the socket 6 each comprise a terminal portion 61 for electrically connecting with the circuit board and a mating portion 62 integrally extending from the terminal portion 61. The mating portion 62 symmetrically defines a pair of spring arms extending from opposite sides thereof. Receiving portions 621 are formed on the spring arms for receiving the pin 7 of the CPU. The distance between the two receiving portions 621 is larger than the diameter of the pin 7 whereby the pin 7 is received between the receiving portions 621 without any contact therebetween for implementing zero insertion force. Engaging portions 622 extend from the receiving portions 621. The distance between the engaging portions 622 is smaller than the diameter of the pin 7 of the CPU. Thus, the pin 7 is secured therebetween to implement electrical connection when the CPU is moved to an engaged position. However, when the pin 7 of the CPU is not located at a predetermined position, improper connection with the engaging potions 622 of the contact 60 results. Thus, the contacts 60 of the socket can not ensure properly mating with the pins 7 of the CPU. In addition, since the spring arms and the pin 7 define a shunt-wound electrical connection, a contact resistance bulk of the symmetrical spring arms is large relative to non-symmetrical spring arms. Thus, the contact resistance bulk of the mating portion 62 is large.